The 36-year-old said she had been freed because she had applied for a pardon.

"Prison by itself is a very horrible place, especially for me the time I spent alone," she said.

"Now I am free, I am back to my family and my daughter, I am very elated."

The BBC's Uduak Amimo in Addis Ababa says hundreds of her supporters began cheering and singing when she arrived, accompanied by her elderly mother and young daughter.

At The Scene

By Uduak AmimoBBC News, Addis Ababa

Hundreds of men and women lined the route to Birtukan Mideksa's family home, which they had decorated with ceremonial grass and Ethiopian flags. Some carried flowers, others burned incense.

Young men sang and danced as the prison car arrived and there were emotional scenes as she entered the house, although in the crush, her young daughter was left outside and became upset.

Ms Birtukan, who has been nominated by the European parliament for the 2010 Sakharov Prize given to individuals who make significant contributions to the struggle for human rights, told journalists she was relieved to be free but would not comment on her future plans.

But the publication of her pardon request, in which she reportedly apologises for wrongs she had done, suggests the authorities have taken every precaution to ensure she will not pose any significant political threat.